Process for preventing vaselation of unhydrogenated vegetable shortening



United States Patent PROCESS FOR PREVENTING VASELATION OF UN- HYDROGENATED VEGETABLE SHORTENING Wales H. Newby and Hanson L. Guidry, Opelousas, La., assignors to Cotton lroducts Co., Inc., Opelonsas, La., a corporation of Louisiana No Drawing. Application May 12, 1952,

Serial No. 287,416

1 Claim. (Cl. 99-163) The present invention relates to the production of an improved vegetable shortening of the blended or compound type containing a high proportion of unhydrogenated oil so that it will have a greatly extended shelf life over similar blended vegetable shortenings.

At the present time there are two general types of vegetable shortenings on the market. They are known respectively as compound or blended shortenings and allhydrogenated shortenings. In composition, the compound or blended shortenings consist of a relatively small proportion, from 5 to 15 per cent, of highly hydrogenated vegetable oil (one of 15.0 iodine value or less), combined with a relatively large proportion, 85 to 95 per cent, of unhydrogenated or very slightly hydrogenated oil; whereas, the all-hydrogenated shortenings are composed only of oils which have received a considerable addition of hydrogen.

Blended shortenings possess the advantages of low manufacturing costs and a wider plastic range over the all-hydrogenated shortenings. However, they have heretofore suffered from an extremely short shelf life due to their tendency to develop yellowish streaks and spots when stored for any length of time.

This streaked or spotted condition which develops in ordinary compound or blended shortenings is well known in the industry where it is called by dilferent terms such as separation, break down, storage streaking, vaselation and age streaking. However, vaselation is probably the most specific and descriptive term since the material causing the streaks or spots develops an appearance similar to ordinary Vaseline. Although a high proportion of hydrogenated oils in the shortening will eifectively prevent vaselation, for those vegetable shortening processers who do not have hydrogenation facilities vaselation of the shortening presents a major problem since once vaselation becomes apparent, the shortening is no longer saleable. 7

Accordingly, it is the primary object of this invention to provide a process for the production of blended vegetable shortenings that will prevent vaselation in the shortening blocks for longer periods of time than were heretofore believed possible.

This object is accomplished through recognition of the heretofore undisclosed fact that vaselation does not occur until a peroxide value of 25.0 milliequivalents per one thousand grams of fat is reached. Thus, any preparation or procedure which will hold the peroxide value below this value of 25.0 milliequivaleuts per thousand grams of fat will prevent vaselation. In this connection, it might be noted that although there are several methods for expressing the peroxide value of an oil or fat, it is to be understood that the definition given above will be used throughout this specification.

Therefore, it is the further object of this invention, ancillary to the primary object, to add anti-oxidants to blended or compound vegetable shortenings to maintain the peroxide value of the shortening below 25.0 for greatly extended periods of time. x

2,726,159 Patented Dec. 6, 1955 In an examination of a number of compound vegetable shortening samples which had been in commercial storage for sometime, it was noted that the fatty materials comprising the actual streak or spot of vaselation was much higher in peroxide value than the balance of the shortening block. Furthermore, there appeared to be a definite peroxide value at which streaks and spots begin to form and this peroxide value was far short of the accepted rancid point. Subsequent examination of similar samples stored in individual paper cartons setting on open shelves confirmed the fact that vaselation spots do not appear until a definite peroxide level is reached.

Some typical laboratory experiments made to illustrate the above observation are as follows. Each of these samples contained approximately unhydrogenated cotton seed oil and 15% hydrogenated oil.

SAMPLES STORED IN PAPER CARTONS AT F.

Days Peroxide Appearance of Stored Value 1 vaselation 28 37. 3 Plainly spotted. 28 26. 2 None. 30 34. 2 Plainly spotted. 27 32. 9 Slight. 33 29. 4 Bearly perceptable.

SAMPLES STORED IN PAPER CARTONS AT 60 F.

Days Peroxide Ap earance of Sample Stored Value 1 V ziselation 139 29. 2 None. 161 37. 2 Plainly Spotted. 138 23 4 None. 168 26 4 Do. 137 29 3 Do. 159 5 6 Plainly Spotted.

Calculated as mini-equivalents 1000 grams of fat.

From the above, it is apparent that no spot or streak of vaselation appeared in any sample with any peroxide value below 25.0 and that in no case was there a plainly evident spot below 30.0. On the other hand, no sample contained a peroxide value much above 30.0 without the appearance of a streak or spot of vaselation somewhere on the block.

At this point, it is important to note that the development of vaselation streaks is a phenomenon entirely different from rancidity 'in thenormally accepted sense. Apparently the development of vaselation streaks parallels peroxide formation but is not dependent on it. According to Beadle writing in Oil and Soap, vol. 23, page 33, 1946:Compound vegetable shortening becomes rancid at a peroxide value of in the Swifts accelerated stavaselation occurs at the same peroxidelevel regardless of the temperature under which the peroxides were developed, or as will be seen later whether anti-oxidants are present, whereas rancid odors develop at different levels of peroxide values dependent on the conditions under which the peroxide was developed.

We have found that by holding the peroxide value down below 25.0 through use of a combination of propyl gallate and citric acid we can prevent vaselation of compound vegetable shortening for much longer storage periods than were heretofore believed possible. 1

' Example N0. 1.In one series of tests, .025 per cent In other words, compound vegetable shorten 3 of propyl gallate and a'like amount of citric acid by weight per 20,000 pounds 'batch of' deodorized-vegctable compound were placed in a deodorizer filter press and 20,000 pounds of deodorized vegetable compound containing.approximately 85% unhydrogenated cotton seed oil was filtered through the .press at a temperature of about 170 F. After it was all filtered, a portion of the resultant compound was run through the solidifying equipment to collect samples. The balance of .the resultant compound was then mixed with some of the same shortening containing no propyl .gallate or citric acid and this mixture was then run through the solidifying equipment. Samples of these two experimental'lots were then compared in controlled storage tests to similar packagesof shortening of vexactly the same composition but without any added propyl gallate or citric acid, which similar packages were utilized asa controlledcomparison. This mixing plus the control samples resulted in four different type samples having the following percentages by weight of propyl gallate and citric acid.

Control No propyl gallate or citric acid.

1 Approximately 005% propyl gallate and citric acid. 2.. Approximately 015% propyl gallato and citric acid.

Approximately 025% propyl gallate and citric acid.

Storage tests at 95 gave the following results:

Table I 05 STORAGE RESULTS seen that by utilizing a proper mixture of propyl gallate --and citric acid "to hold the peroxide value under this figure, it was possible to prevent the formation of streaks for periods up to 250 days at 95 F. as compared to 26 days for untreated shortening. With the room temperature tests, the comparison is 10 months as against less than 3 months for untreated shortening.

Subsequent experimental work demonstrated that dissolving the propyl gallate and the citric acid by placing them directly into the deodorizer press was not a satistactory procedure since the resulting solution was not uniform and considerable amounts of the anti-oxidants remained in the press. Eventually it was found, that by dissolving the anti-oxidants in volatile solvents and introducing the solutions into the shortening while it was still in the deodorizer a much better solution could be obtained with the use of less propyl gallate. The high temperature and violent agitation inside the deodorizer dissolves the anti-oxidants and the high vacuum ,in the deodorizer evaporates off the relatively more volatile elements. It is necessary, however, to have a connection 7 into the deodorizer such that the anti-oxidants can be Sample Control #1 Percent propyl .gallate and citric a Peroxide value at filling Peroxide value at end of 5 days..." Peroxide value at end of 20 days Peroxide value at end of 26 days... Appearance after 26 dayS Peroxide value at 49 days Appearance at 49 days Peroxide value at d: Appearance at 70 days..." Peroxide value at 140 days. Appearance at 140 days. Peroxide value at 169 days. Appearance at 169 days r.

Peroxide value at 264 days Appearance at, 264 days 27.9. Slight streak.

Although encouraging, the above resultswere still not representative of normal shelf life since normal shelf temperature is more in the neighborhood of 7080. Also, cartons resting individually in rapidly circulated warm air are subjected to somewhat diiferent conditions than when stored in sealed cases. Accordingly, two cases were filled with cartons from the above samples and then sealed atthe beginning of the above tests. These cases were opened and examined at'spaced intervals 'with the following results:

Table II R0031 TEAIPERATURE STORAGE TESTi;

114 days 150 days 305 days Sample f ii g Appearance 3 332 Appearance g ggg Appearance Verybadly streaked Slightly streaked. Good Slight streak.

Good.

From the above tables, it can be seen that whether tested at 95 F. in individual cartons or at room tempcrature insealed cases no streaks .o,r spots of vaselation appeared on any .of the .treated samples .nntil peroxide values in excess of 25.0 were reached. Also, it can be high vacuum, flashes off the solvents before filtration is begun without distilling any appreciable amount of propyl gallate. The .amountsofpropyl gallate and citric acid are determinedby weight per.20,000-pound.batchpf Negetable shortening containing approximately unhydrogenated cotton seed oil. The storage results are as follows:

The samples treated in. Table No. III in no case developed more than 11.7 mini-equivalents of peroxide per 1000 grams of fat in up to 105 days of storage and showed no spots up to above 160 days of storage.

We have also discovered that the initial peroxide value of the shortening when solidified has an important bearing on the subsequent rise in peroxide value and, therefore, on the length of time required for vaselation to appear. This can be seen by comparing the experimental results shown in Tables IV and V.

Table IV KOMPOUND SHOR'IENING WITHOUT PROPYL GALLA'IE AND OITRIC ACID Potential Peroxide Peroxide tability value after Sample Value at galnst 30 days at filling 95 F.

1 As measured in hours at 97.7 0. required to reach a peroxide value of 100 mini-equivalents per 1000 grams of fat in the Swifts Accelerated Stability Apparatus.

Table V COMPOUND SHORTENING TREATED WITH CIT RIC ACID AND PROPYL GALLATE AS IN EXAMPLE III Potential Peroxide Sample g 332 3: 13 3 agams eye a rancidity 1 fining 95 F.

1 (See footnote for Table IV.)

It is clear from these results that the peroxide value at the time of packaging is a better index of the future peroxide value after storage than is the stability as estab- 6 lished by the AOM method in the apparatus usually referred to as the Swifts accelerated stability apparatus (Oil and Soap, volume 10, pages -109, 1933). The AOM test is the most generally accepted method of determining relative stability of fats against oxidative rancidity; nevertheless, sample #2 has a much lowerfperoxide value after storage for 30 days than sample #1 in spite of the fact that its stability was lower as measured by the above method. It is apparent, therefore, that sample #2 was more resistant to vaselation than sample #1 and visual examination of the samples after storage at 95 F. for 30 days confirmed this fact. The same comparison can be made on samples 3 and 4. In the case of the shortening containing propyl gallate, the differences are less but the trend is the same and it continues to be the same for at least 90 days of storage. From this, it is apparent that packaging of the shortening at the lowest possible peroxide value greatly retards vaselation; and that compound shortening packaged at a peroxide value of less than 1.0 will have a relatively better resistance to vaselation than those packaged above this value.

This is another reason why propyl gallate or other anti-oxidants should be introduced into the fat while still under vacuum in a deodorizer. All oils will come out of a properly designed and operated deodorizer at essentially zero peroxide value. rapidly in contact with air at any temperature above 90 F. Therefore, since compound shortening must be filtered at F. or higher it will develop an appreciable peroxide content within a few hours, or even minutes. Consequently, it is important that any anti-oxidants used be added before the shortening comes in contact with the air after deodorization.

In view of the foregoing description, it is believed that a clear understanding of the invention will be quite apparent to those skilled in the art, and accordingly, a more detailed description is believed to be unnecessary.

What is claimed as new is:

The process of retarding the appearance of vaselation streaks in vegetable shortening comprising a large proportion of unhydrogenated oils which includes reducing the peroxide value of the oils to zero in a vacuum; cooling the oils to a temperature of at least 350 F., adding a small amount of propyl gallate and citric acid to the oils, injecting steam into the oils to dissolve the V propyl gallate and citric acid in the oils while maintaining the oils in the vacuum; and then removing the oils from the vacuum.

References Cited in the file of this patent UNITED STATES PATENTS 2,374,234 Phelps et al. Apr. 24, 1945 

